//
//  Disk.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 18/09/2016.
//  Copyright 2016 Thomas Harte. All rights reserved.
//

#include "Disk.hpp"

#include "Storage/Disk/Controller/DiskController.hpp"
#include "Storage/Disk/Encodings/MFM/Parser.hpp"
#include "Numeric/CRC.hpp"

#include <algorithm>
#include <cstring>

using namespace Analyser::Static::Acorn;

std::unique_ptr<Catalogue> Analyser::Static::Acorn::GetDFSCatalogue(const std::shared_ptr<Storage::Disk::Disk> &disk) {
	// c.f. http://beebwiki.mdfs.net/Acorn_DFS_disc_format
	auto catalogue = std::make_unique<Catalogue>();
	Storage::Encodings::MFM::Parser parser(Storage::Encodings::MFM::Density::Single, disk);

	const Storage::Encodings::MFM::Sector *const names = parser.sector(0, 0, 0);
	const Storage::Encodings::MFM::Sector *const details = parser.sector(0, 0, 1);

	if(!names || !details) return nullptr;
	if(names->samples.empty() || details->samples.empty()) return nullptr;
	if(names->samples[0].size() != 256 || details->samples[0].size() != 256) return nullptr;

	uint8_t final_file_offset = details->samples[0][5];
	if(final_file_offset&7) return nullptr;
	if(final_file_offset < 8) return nullptr;

	char disk_name[13];
	snprintf(disk_name, 13, "%.8s%.4s", &names->samples[0][0], &details->samples[0][0]);
	catalogue->name = disk_name;

	switch((details->samples[0][6] >> 4)&3) {
		case 0: catalogue->bootOption = Catalogue::BootOption::None;		break;
		case 1: catalogue->bootOption = Catalogue::BootOption::LoadBOOT;	break;
		case 2: catalogue->bootOption = Catalogue::BootOption::RunBOOT;		break;
		case 3: catalogue->bootOption = Catalogue::BootOption::ExecBOOT;	break;
	}

	for(std::size_t file_offset = 8; file_offset <= final_file_offset; file_offset += 8) {
		File new_file;
		char name[10];
		snprintf(name, 10, "%c.%.7s", names->samples[0][file_offset + 7] & 0x7f, &names->samples[0][file_offset]);
		new_file.name = name;
		new_file.load_address = uint32_t(
			details->samples[0][file_offset] |
			(details->samples[0][file_offset+1] << 8) |
			((details->samples[0][file_offset+6]&0x0c) << 14)
		);
		new_file.execution_address = uint32_t(
			details->samples[0][file_offset+2] |
			(details->samples[0][file_offset+3] << 8) |
			((details->samples[0][file_offset+6]&0xc0) << 10)
		);
		if(names->samples[0][file_offset + 7] & 0x80) {
			// File is locked; it may not be altered or deleted.
			new_file.flags |= File::Flags::Locked;
		}

		auto data_length = long(
			details->samples[0][file_offset+4] |
			(details->samples[0][file_offset+5] << 8) |
			((details->samples[0][file_offset+6]&0x30) << 12)
		);
		int start_sector = details->samples[0][file_offset+7] | ((details->samples[0][file_offset+6]&0x03) << 8);
		new_file.data.reserve(size_t(data_length));

		if(start_sector < 2) continue;
		while(data_length > 0) {
			const uint8_t sector = uint8_t(start_sector % 10);
			const uint8_t track = uint8_t(start_sector / 10);
			++start_sector;

			const Storage::Encodings::MFM::Sector *next_sector = parser.sector(0, track, sector);
			if(!next_sector) break;

			const long length_from_sector = std::min(data_length, 256l);
			new_file.data.insert(new_file.data.end(), next_sector->samples[0].begin(), next_sector->samples[0].begin() + length_from_sector);
			data_length -= length_from_sector;
		}
		if(!data_length) catalogue->files.push_back(std::move(new_file));
	}

	return catalogue;
}

/*
	Primary resource used: "Acorn 8-Bit ADFS Filesystem Structure";
	http://mdfs.net/Docs/Comp/Disk/Format/ADFS
*/
std::unique_ptr<Catalogue> Analyser::Static::Acorn::GetADFSCatalogue(const std::shared_ptr<Storage::Disk::Disk> &disk) {
	auto catalogue = std::make_unique<Catalogue>();
	Storage::Encodings::MFM::Parser parser(Storage::Encodings::MFM::Density::Double, disk);

	// Grab the second half of the free-space map because it has the boot option in it.
	const Storage::Encodings::MFM::Sector *free_space_map_second_half = parser.sector(0, 0, 1);
	if(!free_space_map_second_half) return nullptr;
	catalogue->has_large_sectors = free_space_map_second_half->samples[0].size() == 1024;

	// Possibility: this is a large-sector disk with an old-style free space map. In which
	// case the above just read the start of the root directory.
	uint8_t first_directory_sector = 2;
	if(catalogue->has_large_sectors && !memcmp(&free_space_map_second_half->samples[0][1], "Hugo", 4)) {
		free_space_map_second_half = parser.sector(0, 0, 0);
		if(!free_space_map_second_half) return nullptr;
		first_directory_sector = 1;
	}

	std::vector<uint8_t> root_directory;
	root_directory.reserve(catalogue->has_large_sectors ? 2*1024 : 5*256);

	for(uint8_t c = first_directory_sector; c < first_directory_sector + (catalogue->has_large_sectors ? 2 : 5); c++) {
		const Storage::Encodings::MFM::Sector *const sector = parser.sector(0, 0, c);
		if(!sector) return nullptr;
		root_directory.insert(root_directory.end(), sector->samples[0].begin(), sector->samples[0].end());
	}

	// Check for end of directory marker.
	if(root_directory[catalogue->has_large_sectors ? 0x7d7 : 0x4cb]) return nullptr;

	// Check for both directory identifiers.
	const uint8_t *const start_id = &root_directory[1];
	const uint8_t *const end_id = &root_directory[root_directory.size() - 5];
	catalogue->is_hugo = !memcmp(start_id, "Hugo", 4) && !memcmp(end_id, "Hugo", 4);
	const bool is_nick = !memcmp(start_id, "Nick", 4) && !memcmp(end_id, "Nick", 4);
	if(!catalogue->is_hugo && !is_nick) {
		return nullptr;
	}

	if(!catalogue->has_large_sectors) {
		// TODO: I don't know where the boot option rests with large sectors.
		switch(free_space_map_second_half->samples[0][0xfd]) {
			default: catalogue->bootOption = Catalogue::BootOption::None;		break;
			case 1: catalogue->bootOption = Catalogue::BootOption::LoadBOOT;	break;
			case 2: catalogue->bootOption = Catalogue::BootOption::RunBOOT;		break;
			case 3: catalogue->bootOption = Catalogue::BootOption::ExecBOOT;	break;
		}
	}

	// Parse the root directory, at least.
	const std::size_t directory_extent = catalogue->has_large_sectors ? 0x7d7 : 0x4cb;
	for(std::size_t file_offset = 0x005; file_offset < directory_extent; file_offset += 0x1a) {
		// Obtain the name, which will be at most ten characters long, and will
		// be terminated by either a NULL character or a \r.
		char name[11]{};
		std::size_t c = 0;
		for(; c < 10; c++) {
			const char next = root_directory[file_offset + c] & 0x7f;
			name[c] = next;
			if(next == '\0' || next == '\r') break;
		}
		name[c] = '\0';

		// An empty name implies the directory has ended; files are always listed in case-insensitive
		// sorted order, with that list being terminated by a '\0'.
		if(name[0] == '\0') break;

		// Populate a file then.
		File new_file;
		new_file.name = name;
		new_file.flags =
			(root_directory[file_offset + 0] & 0x80 ? File::Flags::Readable : 0) |
			(root_directory[file_offset + 1] & 0x80 ? File::Flags::Writable : 0) |
			(root_directory[file_offset + 2] & 0x80 ? File::Flags::Locked : 0) |
			(root_directory[file_offset + 3] & 0x80 ? File::Flags::IsDirectory : 0) |
			(root_directory[file_offset + 4] & 0x80 ? File::Flags::ExecuteOnly : 0) |
			(root_directory[file_offset + 5] & 0x80 ? File::Flags::PubliclyReadable : 0) |
			(root_directory[file_offset + 6] & 0x80 ? File::Flags::PubliclyWritable : 0) |
			(root_directory[file_offset + 7] & 0x80 ? File::Flags::PubliclyExecuteOnly : 0) |
			(root_directory[file_offset + 8] & 0x80 ? File::Flags::IsPrivate : 0);

		new_file.load_address =
			(uint32_t(root_directory[file_offset + 0x0a]) << 0) |
			(uint32_t(root_directory[file_offset + 0x0b]) << 8) |
			(uint32_t(root_directory[file_offset + 0x0c]) << 16) |
			(uint32_t(root_directory[file_offset + 0x0d]) << 24);

		new_file.execution_address =
			(uint32_t(root_directory[file_offset + 0x0e]) << 0) |
			(uint32_t(root_directory[file_offset + 0x0f]) << 8) |
			(uint32_t(root_directory[file_offset + 0x10]) << 16) |
			(uint32_t(root_directory[file_offset + 0x11]) << 24);

		new_file.sequence_number = root_directory[file_offset + 0x19];

		const uint32_t size =
			(uint32_t(root_directory[file_offset + 0x12]) << 0) |
			(uint32_t(root_directory[file_offset + 0x13]) << 8) |
			(uint32_t(root_directory[file_offset + 0x14]) << 16) |
			(uint32_t(root_directory[file_offset + 0x15]) << 24);

		uint32_t start_sector =
			(uint32_t(root_directory[file_offset + 0x16]) << 0) |
			(uint32_t(root_directory[file_offset + 0x17]) << 8) |
			(uint32_t(root_directory[file_offset + 0x18]) << 16);

		new_file.data.reserve(size);
		while(new_file.data.size() < size) {
			const Storage::Encodings::MFM::Sector *const sector =
				parser.sector(start_sector / (80 * 16), (start_sector / 16) % 80, start_sector % 16);
			if(!sector) break;

			const auto length_from_sector = std::min(size - new_file.data.size(), sector->samples[0].size());
			new_file.data.insert(
				new_file.data.end(),
				sector->samples[0].begin(),
				sector->samples[0].begin() + ssize_t(length_from_sector)
			);
			++start_sector;
		}

		catalogue->files.push_back(std::move(new_file));
	}

	// Include the directory title.
	const char *title, *name;
	if(catalogue->has_large_sectors) {
		title = reinterpret_cast<const char *>(&root_directory[0x7dd]);
		name = reinterpret_cast<const char *>(&root_directory[0x7f0]);
	} else {
		title = reinterpret_cast<const char *>(&root_directory[0x4d9]);
		name = reinterpret_cast<const char *>(&root_directory[0x4cc]);
	}

	catalogue->name = std::string(title, strnlen(title, 19));
	if(catalogue->name.empty() || catalogue->name == "$") {
		catalogue->name = std::string(name, strnlen(name, 10));
	}

	return catalogue;
}
